.\"	$OpenBSD: csqrt.3,v 1.2 2013/06/05 03:40:26 tedu Exp $
.\"
.\" Copyright (c) 2011 Martynas Venckus <martynas@openbsd.org>
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.Dd $Mdocdate: June 5 2013 $
.Dt CSQRT 3
.Os
.Sh NAME
.Nm csqrt ,
.Nm csqrtf ,
.Nm csqrtl
.Nd complex square root
.Sh SYNOPSIS
.In complex.h
.Ft double complex
.Fn csqrt "double complex z"
.Ft float complex
.Fn csqrtf "float complex z"
.Ft long double complex
.Fn csqrtl "long double complex z"
.Sh DESCRIPTION
The
.Fn csqrt ,
.Fn csqrtf
and
.Fn csqrtl
functions compute the complex square root of
.Fa z .
.Pp
If
.Fa z
= x + iy, then
.Bd -literal -offset indent
Re csqrt(z) = [ (|z| + x) / 2 ]^(1/2).
Im csqrt(z) = [ (|z| - x) / 2 ]^(1/2).
.Ed
.Pp
Note that -csqrt(z) is also a square root of
.Fa z .
The root chosen
is always in the right half plane and Im csqrt(z) has the same sign
as y.
.Sh RETURN VALUES
The
.Fn csqrt ,
.Fn csqrtf
and
.Fn csqrtl
functions return the complex square root of
.Fa z .
.Sh SEE ALSO
.Xr cpow 3
.Sh STANDARDS
The
.Fn csqrt ,
.Fn csqrtf
and
.Fn csqrtl
functions conform to
.St -isoC-99 .
